Impossible to answer- value depends on make, model and condition- and with some guns, we can only make an educated guess. Jean Marie Prosper Schlemmer was a gun maker in Liege Belgium in the 1925-1935 time period. He died in Liege in the 1950s. The very few Prosper Schlemmer guns I have seen were nicely made, but so scarce that it is difficult to find comparable sales. You will need to visit a knowledgeable gunsmith or gun show in your area for a hands on appraisal.
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